Rotor for multistation photometric analyzer

ABSTRACT

AN IMPROVED ROTOR FOR A MULTISTATION PHOTMETRIC ANALYZER WHICH IS CAPABLE OF OPERATION WITHOUT GRAVITATIONAL ASSISTANCE TO EFFECT TRANSFER OR RETENTION OF LIQUIDS. THE ROTOR COMPRISES A LAMINATED DISK-SHAPED MEMBER WITH A CENTRAL OPAQUE DISK SANDWICHED BETWEEN OUTER TRANSPARENT DISKS. THE CENTRAL DISK IS PROVIDED WITH A CIRCULAR ARRAY OF AXIALLY EXTENDING APERTURES WHICH FORM SAMPLE ANALYSIS CUVETTES WHEN THAT DISK IS SANDWICHED BETWEEN THE OUTER TRANSPARENT DISKS. CENTRAL LOADING PORTS EXTEND THROUGH EACH OUTER TRANSPARENT DISK IN REGISTER WITH RESPECTIVE DISTRIBUTION CHAMBERS FORMED IN THE OPPOSING END FACES OF THE CENTRAL DISK. PASSAGEWAYS EXTEND FROM EACH DISTRIBUTION CHAMBER TO EACH SAMPLE ANALYSIS CUVETTE FOR ADDING SAMPLE AND REAGENT LIQUIDS TO THE SAMPLE ANALYSIS CUVETTES. MEANS ARE PROVIDED FOR UNIFORMLY DISTRIBUTING SAMPLE AND REAGENT LIQUIDS TO THE SAMPLE ANALYSIS CUVETTES WHILE THE ROTOR IS IN OPERATION.

Filed Deb. 1971 July .10, 1973 V J. c. MNLEN ,9

ROTOR FOR MULTISTAGE PHOTOMETP-IC ANALYZER 3 Sheets-Sheet l 1 l l 5 I 4 11 E in I f 8 l a 2/ 13 l I H 9 y 1973 J. c MAILEN 3,744,975

ROTOR FOR MULTXS'IAGI'J lHOI'OMI'I'I'HHI ANALYZER I Filed Dec. 9, 1971 Sheets-Sheet Filed Dec. 9, 1971 July 10, 1973 J. c. MAILEN 3,744,975

ROTOR FOR MULTIS'I'AGE PHOTOMETHIC ANALYZER 3 Sheets-Sheet United States Patent O 3,744,975 ROTOR FOR MULTISTATION PHOTOMETRIC ANALYZER James C. Mailen, Oak Ridge, Tenn., assiguor to the United States of America as represented by the United States Atomic Energy Commission Filed Dec. 9, 1971, Ser. No. 206,468 Int. Cl. Gflln 1/10, 21/00, 33/16; Bil-lb 5/12 US. Cl. 23-259 9 Claims ABSTRACT OF THE DISCLOSURE An improved rotor for a multistation photometric analyzer which is capable of operation without gravitational assistance to efiect transfer or retention of liquids. The rotor comprises a laminated disk-shaped member with a central opaque disk sandwiched between outer transparent disks. The central disk is provided with a circular array of axially extending apertures which form sample analysis cuvettes when that disk is sandwiched between the outer transparent disks. Central loading ports extend through each outer transparent disk in register with respective distribution chambers formed in the opposing end faces of the central disk. Passageways extend from each distribution chamber to each sample analysis cuvette for adding sample and reagent liquids to the sample analysis cuvettes. Means are provided for uniformly distributing sample and reagent liquids to the sample analysis cuvettes while the rotor is in operation.

BACKGROUND OF THE INVENTION The invention described herein relates generally to photometers and more particularly to an improved rotor for a multistation photometric analyzer which is capable of operation without gravitational assistance to effect transfer or retention of liquids. It was made in the course of, or under, a contract with the US. Atomic Energy Commission.

The recent development of manner space flights of extended duration has created a need for analytical systems which can rapidly accomplish diverse biochemical analyses of an astronauts body fluids under flight conditions. Such analyses are necessary to provide a continuing indication of the state of the astronauts health so that remedial measures may be taken, if neccesary. 0f particular interest are blood tests including glucose, LDH, SGOT, SGPT, BUN, total protein, alkaline phosphatase, bilirubin, calcium, chloride, sodium, potassium and magnesium. Such tests are normally performed on blood plasma and require prior centrifugation of blood samples to remove red blood cells.

One device which was designed to rapidly accomplish a multiplicity of simultaneous biochemical analyses is described in US. Pat. No. 3,586,484 issued to common assignee on June 22, 1971, in the name of Norman G. Anderson. According to that patent, an analytical photometer is provided wherein precipitates are removed from a multiplicity of samples by centrifugation prior to transfer of the samples to respective cuvettes in a rotary cuvette system for photometric measurement. A central transfer disk is provided with chambers which gravitationally retain sample and reactant liquids when at rest, and release the liquids to respective sedimentation chambers upon rotation. Following sedimentation, the transfer disk is brought to rest and supernatant removed by gravity flow to a third series of chambers. The supernatant may then be transferred centrifugally to respective cuvettes in a rotary cuvette system surrounding the disk. A light source and detector are aligned with transparent windows in the cuvettes to determine chemical species concentrations by light absorbancy in the samples contained in the cuvettes.

Means are provided for receiving the output of the detector and individually indicating the phototransmittance of samples Within the cuvettes.

Although the above-described analytical photometer an similar devices incorporating multistation rotary cuvette systems are becoming widely used in various laboratories because of their ability to rapidly and accurately analyze large numbers of samples, they are unsuitable for space application because they rely on gravitational assistance to retain or transfer liquids at some point in their load-to-measurement operating cycle. Although space vehicles in orbital and lunar space flights are subject to gravitational attraction in the same manner as is all matter in the universe, they experience the condition known as weightlessness because they are always (expect during engine operation or re-entry) freely falling with an acceleration determined by the net gravitational force which they experience. Under such conditions, gravitational force cannot be utilized to transfer or retain liquids.

It is, accordingly, a general object of the invention to provide an improved rotor for a multistation photometric analyzer which is capable of opearation without gravitational assistance to etfect transfer or retention of liquids.

Other objects of the invention will be apparent from an examination of the following description of the invention and the appended drawings.

SUMMARY OF THE INVENTION In accordance with the invention, an improved rotor for a multi-station photometric analyzer is provided which is capable of operation without gravitational assistance to elfect transfer or retention of liquids. The rotor comprises a laminated disk-shaped member with a central opaque disk sandwiched between outer transparent disks. The central disk is provided with a circular array of axially extending apertures which form sample analysis cuvettes when the disk is sandwiched between the outer transparent disks. Central loading ports extend through each outer transparent disk in register with respective distribution chambers formed in the opposing end faces of the central disk. Passages extend from each distribution chamber to each sample analysis cuvette for adding sample and reactant liquids to the cuvettes. Means are provided for uniformly distributing sample and reagent liquids to the sample analysis cuvettes while the rotor is in operation.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical sectional View schematically illustrating a photometric analyzer utilizing the subject rotor.

FIG. 2 is a top plan view of the photometric analyzer of FIG. 1.

FIG. 3 is a plan view of the sample loading side of the subject rotor.

FIG. 4 is an isometric view, sectioned and partially cut away, illustrating the sample loading side of the subject rotor.

FIG. 5 is a plan view of the reagent loading side of the subject rotor.

FIG. 6 is an isometric view, sectioned and partially cut away, illustrating the reagent loading side of the subject rotor.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, initially to FIGS. 1 and 2, a photometric analyzer of the rotary type incorporating a rotor 1 made in accordance with the invention is shown in a simplified schematic manner. As shown, a motor driven rotor support housing 2 has a generally cylindrical body portion 3 terminating in a circular fiat plate portion 4. An annular upstanding rim 5 integrally fixed to flat plate portion 4 provides lateral restraint to rotor 1. Means (not shown), such as a key and magnet are used to prevent relative rotation between rotor 1 and platform 2 and to secure the rotor to the platform under weightless flight conditions while permitting relatively effortless manual removal of the rotor when desired.

A photometric light source 6 provides a light beam of constant intensity intersecting rotor 1 at a point corresponding to the radial positions of sample analysis cuvettes 7. Apertures 8 are provided in flat plate portion 4 of housing 2 in axial register with the sample analysis cuvettes 7. The light beam from light source 6, indicated by a broken line in FIG. 1, is aligned in such a manner so as to be transmitted through each aperture 8 and cuvette 7 as they pass through the beam.

Electronic photodetecting means 9 is disposed below rotor 1 and flat plate portion 4 of housing 2 where it is aligned to receive light transmitted through the sample analysis cuvettes during rotation. Photodetecting means 9 comprise a photomultiplier tube and is designed to respond electrically with an output proportional to the intensity of the light transmitted through the cuvettes.

Interposed between photodetecting means 9 and fiat plate portion 4 of housing 2 is an adjustable filter selector 11 containing a plurality of light filters 12 having different light transmission characteristics. A spring loaded indexing mechanism 13 engages appropriately spaced depressions in adjustable filter selector 11 to secure any one of light filters 12 in axial alignment with light source 6 and photodetecting means 9.

As shown, a solenoid disk brake assembly 14 is provided for rapid braking of rotatable housing 2 by engaging the radially outermost portion of flat plate portion 4. A pickup head rotor position indicator 15 generates pulses by means of photodiodes which are illuminated through holes 16 drilled through housing 2. The pulses are used by means of appropirate circuitry to provide rotor speed control and correlation of the light pulses transmitted through the sample analyses cuvettes to rotor position.

Referring now to FIGS. 3 and 4, a plan and perspective view of the sample loading side of rotor 1 are shown, respectively. In construction, the rotor is of laminated design with a central, preferably opaque, plastic disk 17 sandwiched between outer transparent plastic disks 18 and 19. A circular array of axially extending apertures are provided through disk 17 to serve as sample analysis cuvettes 7. As shown, disk 17 is provided with a series of generally radially oriented depressions extending from each cuvette 7 to a central sample distribution chamber 20. Centrally located, tapered, sample. loading port 21 extends through disk 17 in register with sample distribution chamber 20.

Radially extending sample distribution passageways 22, one for each sample analysis cuvette 7, intersect at the periphery of sample distribution chamber 20 to create a saw-tooth or serrated edge effect which provides a sub stantially equal distribution of sample liquid into passageways 22 when rotor 1 is rotating and sample liquid is injected through loading port 21. Overflow channels 23 and overflow collection cavities 24 may be provided to limit the volume of liquid retained in each passageway 22 and further ensure equal distribution of sample liquid in those channels. Passageways 22 are of capillary size to prevent loss of sample liquid during conditions of weightlessness and when the rotor is not spinning.

Extending from a point near but spaced from the radial extremity of each passageway 22 is a connecting passageway 25 which terminates at a corresponding sample analyses cuvette. Each passageway 25 is folded to extend radially inward from its point of intersection with a passageway 22 and then radially outward to a cuvette. The folded configuration prevents direct passage of sample fluid to cuvettes 7 after it has been distributed to passageways 22 as the acceleration induced pressure head of the sample liquid in each passageway 22 is balanced by the pressure head of fluid in the inwardly extending leg 26 of each corresponding passageway 25. As noted above, each passageway 25 intersects a corresponding passageway 22 at a point spaced from its radial extremity. This creates a trap where particulates in the sample liquid may be centrifugally compacted and retained so that only the purely liquid component of the sample is passed on to the sample analysis cuvettes.

Referring now to FIGS. 5 and 6, a plan and perspective view of the reagent loading side of the rotor 1 are shown.

A reagent distribution chamber 27 communicates with cuvettes 7 through radially extending reagent distribution passageways 28 which are of capillary size to retain liquids in the cuvettes when the rotor is not spinning and under conditions of weightlessness. Reagent distribution chamber 27 is provided with a saw-tooth or serrated edge effect by the intersection of passageways 28 in the same manner as is sample distribution chamber 20. A reagent loading port 29 extends through disk 19 in register with reagent distribution chamber 27.

In operation, a single reagent may be injected through reagent loading port 29 into the spinning rotor in the form of a solution. Once in the sample analysis cuvettes, capillary action retains the reagent liquid even under conditions of weightlessness and non-rotation. Use of a single reagent would limit the system to the analysis of replicate aliquots for a single constituent, however. According to a preferred operation, different reagents are preloaded into the cuvettes and lyophilized. When a photometric analysis is to be made, the lyophilized reagents are solubilized by injecting water or bufler into the spinning rotor in the manner described above. Such operation permits multiple chemical analyses to be made on a single blood sample.

Sample liquid such as blood is next injected into the spinning rotor by any suitable means such as a hypodermic syringe inserted through sample loading port 21 so as to discharge into sample distribution chamber 20. The sample flows radially outward through sample distribution passageways 22 until it reaches and fills the end of the passageways and overflows into overflow channels 23 and collection cavities 24. Rotor rotation is continued at suflicient speed to separate red blood cells, in the case of a blood sample, and trap them in the outermost ends of passageways 22. Air pressure is then applied through sample loading port 21 to force the plasma, remaining after the red blood cells have been centrifugally removed and trapped, through passageways 25 into the sample analysis cuvettes 7. Alternatively, a liquid such as water or saline solution can be injected to displace the plasma. Once in the cuvettes, the plasma and reactants mix and are photometrically analyzed.

Following the photometric analyses, the entire rotor may be discarded and a new rotor inserted in the support housing formultiple tests on another sample. As desired, sample and reagent material in the discarded rotor will remain in that rotor even under weightless conditions due to capillary action in passageways 22 and 28. The loading ports can be permanently plugged to furnish additional gontainment or the rotor placed in a leak-tight plastic EXAMPLE Rotors have been made in accordance with the invention for use in whole blood analysis which can be operated without liquid spillage either under space flight conditions of weightlessness or terrestrially. The rotors, which are substantially as shown in the drawings and described below in reference to the drawings, were made from plastic disks having overall diameters within the range from 2.25 to 3.5 inches, each center disk 17 having a thickness of 0.2 inch and outer disks 18 and 19 a thickness of 0.125.

To form the reagent loading side of each rotor, the central disk 17 was machined on one side to form reagent distribution chamber 27 measuring a distance A of inch between the radially innermost points formed by intersecting passageways 28. In the smaller, 2.25 inch diameter rotors, eight, equally spaced holes were drilled through each center disk 17 near its periphery on a common circle 1% inch in diameter. These holes determined the volume of the cuvettes (0.006 cubic inch or 0.1 cubic centimeter). Capillary passageways to permit liquid transfer on the reagent loading side were provided by machining grooves having a depth and with B of inch into the center disk.

To form the sample loading side of the rotor, the opposite side of disk 17 was machined to form a replica of the distribution chamber on the reagent loading side. Passageways 22 were machined to a depth of inch and a width C of inch. Folded connecting passageways 25, which were machined with a width D inch and a & inch depth to provide a capillary effect, intersect passageways 22 at a distance E of /8 inch from their radial extremities.

The transparent disks were cemented to the opaque disk to cover the open passageways and holes formed therein and form a closed system of sample and reagent distribution passageways and sample analysis cuvettes. Wax coatings were applied to the machined passageways and holes to prevent cement from flowing into those places.

Rotors having a 3% inch diameter and 17 cuvettes were fabricated in a manner similar to that described above in reference to the 2.25 inch diameter rotors. The dimensions of the cuvettes, distribution chambers and rotor thickness were identical to those in the smaller rotor. The lengths of the various passageways were extended to accommodate the larger radius of the 3 /2 inch rotor.

The above description of one embodiment of the invention should not be interpreted in a limiting sense. For example, the rotor disk may have more or less cuvettes than the eight shown and may be fabricated of different materials using diiferent fabrication techniques such as pressure molding. It is intended rather that the invention be limited only by the scope of the appended claims.

What is claimed is:

1. An improved rotor for a photometric solution analyzer of the rotary cuvette type suitable for operation without gravitational assistance to efiect transfer or retention of liquids; the improved rotor comprising a generally disk-shaped member defining:

(a) a circular array of sample analysis cuvettes for accepting liquid samples and reagents, said diskshaped member having transparent walls adjacent said sample analysis cuvettes for permitting the passage of light therethrough;

(b) first and second axially displaced distribution chambers centrally located within said disk-shaped member for receiving liquids to be distributed to said sample analysis cuvettes;

(c) respective first and second distribution passageways communicating, in parallel, between said first and second distribution chambers and said sample analysis cuvettes for distributing liquids from said distribution chambers to said cuvettes during rotation of said rotor, one each of said first and second distribution passageways communicating with each of said sample analysis cuvettes, at least part of each of said first and second distribution passageways being sized to act as a capillary tube; and

(d) first and second inlet ports communicating, respectively, between said first and second distribution chambers and opposite axial end faces of said diskshaped member to enable said distribution chambers to be loaded with liquids during rotation of said rotor.

2. The improved rotor of claim 1 wherein said first distribution passageways each comprise a first generally radially outward extending passageway portion communicating with said first distribution chamber and a second capillary size connecting passageway portion communicating between said first portion and a corresponding sample analysis cuvette, said second portion intersecting said first portion at a point radially inward from the radially outermost extremity of said first portion, said second portion extending generally radially inward from its point of intersection with said first portion and then generally radially outward to said sample analysis cuvette.

3. The improvement of claim 2 wherein an overflow passageway intersects said first portion of each of said first distribution passageways at a point radially inward from the radial extremity of said first portion.

4. The improvement of claim 3 wherein collection cavities are provided within said disk-shaped member at the end of each overflow passageway.

5. The improvement of claim 3 wherein said overflow passageway intersects said first portion at a point radially inward from the point where said second portion intersects said first portion.

6. The improved rotor of claim 1 wherein each of said first distribution passageways intersects with adjacent first distribution passageways at an acute angle so as to form a serrated periphery about said first distribution chamber.

7. The improved rotor of claim 1 wherein each of said second distribution passageways intersects with adjacent second distribution passageways at an acute angle so as to form a serrated periphery about said second distribution chamber.

8. The improved rotor of claim 1 wherein said rotor is of laminated construction with a central opaque disk sandwiched between transparent disks.

9. The improvement of claim 8 wherein said sample analysis cuvettes comprise axial perforations through said central opaque disk.

References Cited UNITED STATES PATENTS 3,586,484 6/1971 Anderson 23259 X 3,679,367 7/1972 Negersmith et al. 23292 X 3,681,029 8/1972 Shapiro 23259 MORRIS O. WOLK, Primary Examiner R. E. SERWIN, Assistant Examiner US. Cl. X.R.

23230 B, 253 R; 233-26, 2502l8; 35639 

